It is known practice in connection with certain medical treatments to drive a needle having one of a number of different shapes into the body of a patient, the needle being generally shaped in the form of a skin penetrating dart. It is also known sometimes to use such needles in place of electrodes for the purpose of administering treatments by electrical currents.
The insertion by hand of a needle of the type in question requires considerable skill, and moreover, it involves more than negligable risk of infection at the point of insertion in spite of care exercised in sterilizing the needles themselves and the hands of the operator.